United and City support for Borussia Dortmund
Investigators treat attack as attempted murder
Police are investigating whether a bomb attack on Borussia Dortmund's team bus could be linked to Islamist terror, German media has reported.
Three explosions occurred as the Dortmund squad were travelling to the Signal Iduna Park stadium for Tuesday's Champions League quarter-final first leg.
According to Suddeutsche Zeitung and German press agency Dpa, a letter found near the scene referred to 2016's attack on a Berlin market which was carried out by a Daesh-inspired terrorist and the fact that German surveillance aircraft are being used in Syria.
The attack left Dortmund defender Marc Bartra requiring surgery on a broken bone in his wrist.
United and City have both tweeted their support: